[MPlayer-users] Re: [MEncoder] Synchonization lost when using Vorbis in a OGM
Jonathan Rogers
jonner at teegra.net
Wed Jun 18 02:23:12 CEST 2003
Rodolfo J. Quesada wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> Hi,
>
> This is my first post to this list... As I had been looking for a long
> time how to deal with a problem I got recently...
>
> I'm trying to compress some VOBs copied with vobcopy, and after that,
> dump the audio, convert it to Vorbis, and mux it all, with ogmmerge to
> get a nice OGM.
>
> The problem is, that those VOBs after starting mencoder, keeps saying
> that there was duplicate frames, enters and leaves telecine mode, it
> jumps from 23.976 to 29.970 in those changes... All of that things are
> expected by the nature of the DVD, when I got to the final AVI, with an
> AC3 audio track (-oac copy), the A-V sync is always around 0.000, with a
> few tens of milliseconds changes... That's still fine...
>
> Then I dump the PCM audio...
>
> cat *.VOB | mplayer -vc null -vo null -ao pcm -aofile audio.wav
>
> And I get a pretty big PCM file... Then I encode it...
>
> oggenc -q0 audio.wav
>
> And got an audio.ogg file...
>
> Then, I merge it...
>
> ogmmerge -A video.avi audio.ogg -o pelicula.ogm
>
> And when I play it with MPlayer, the sync ratio jumps up to 15 seconds,
> in some scenes where the telecine mode was enabled... It gets
> desynchronized all the way, in the plain old 29.970fps scenes, the audio
> is synced, but not in the 23.976 ones... I tried it in Windows Media
> Player 6.4, and those scenes not synchonized get blurred or stoped, and
> follows the audio synchronizations nicely, but the video quality is not
> appealing at all... Pretty ugly in fact...
>
> So, the question, somebody has faced this problem before? It can be
> solved?... I really love OGM... The audio is so sweet, even at a -q0
> ratio...
I have a very similar problem. I transcoded a movie from DVD to MPEG-4
which has many cuts between NTSC interlaced video at 29.97 and telecined
film at 23.976. Since there is 29.97 fps video in there, I encoded to
29.97 and used pp=lb.
When I play the AVI containing the encoded video and PCM audio with
mplayer, the sync is good. However, when I play the OGM produced with
the Vorbis audio and ogmmerge, the sync is horrible. The A-V delta gets
up to a second or two by mplayer's admission and according to my eyes
and ears.
In particular, mplayer starts getting out of sync when the movie cuts to
an originally telecined segment. It somewhat regains sync when the movie
cuts back to something that was originally NTSC. During film segments,
mplayer's "A-V" value will sometimes jump from less than one second to
greater than one. If I seek forward, then back to the same spot, sync is
usually restored.
Now, it's time for the kicker. When I play the exact same OGM with Xine,
there are no sync problems. Based on my previous experience with
mplayer's flakiness in seeking and sync of OGM movies and this mess, I
tend to think this is a bug in mplayer. It could be a bug in ogmmerge,
but if so, Xine is somehow working around it.
Jonathan Rogers
More information about the MPlayer-users
mailing list